A terrible incendiary fire occurred at a subway station of South Korea on February 18th, 2003. A number of people fell victim to this terrible accident. After this accident, the interior materials of the Japanese passenger vehicle have been faced with a strong request for re-considering its performance level against a big fire, because the ordinary Japanese standard for the interior materials of a passenger vehicle have been considered only against a small fire like a cigarette. In this background, some flammability test procedures against a big fire were selected from foreign standards for examination. In this paper, based on the selected flammability test procedures, we studied and confirmed the performance level of the Japanese ordinary interior materials. In addition, based on the international movement of required flame retardant for polymer materials, an expected flame retardant technology are also proposed.